U.S. patent number 10,943,946 [Application Number 16/039,177] was granted by the patent office on 2021-03-09 for iled displays with substrate holes.
This patent grant is currently assigned to X Display Company Technology Limited. The grantee listed for this patent is X Display Company Technology Limited. Invention is credited to Ronald S. Cok, Robert R. Rotzoll.
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United States Patent |
10,943,946 |
Rotzoll , et al. |
March 9, 2021 |
iLED displays with substrate holes
Abstract
An inorganic light-emitting diode (iLED) display comprises a
display substrate comprising a display area and one or more holes
extending through the display substrate in the display area and a
plurality of inorganic light-emitting diodes (iLEDs) disposed on,
in, or over the display substrate in a regular array in the display
area. At least some of the iLEDs are disposed between at least some
of the holes in the display area and at least some of the holes are
between at least some of the iLEDs in the display area. The display
substrate can be substantially rigid and the iLED display can a
flexible black sheet laminated, affixed, or adjacent to the display
substrate. One or more audio loudspeakers can be disposed adjacent
to the flexible sheet with the flexible sheet disposed between the
display substrate and the one or more audio loudspeakers.
Inventors: |
Rotzoll; Robert R. (Colorado
Springs, CO), Cok; Ronald S. (Rochester, NY) |
Applicant: |
Name |
City |
State |
Country |
Type |
X Display Company Technology Limited |
Dublin |
N/A |
IE |
|
|
Assignee: |
X Display Company Technology
Limited (Dublin, IE)
|
Family
ID: |
1000005411557 |
Appl.
No.: |
16/039,177 |
Filed: |
July 18, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190027534 A1 |
Jan 24, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62535307 |
Jul 21, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L
25/0753 (20130101); H01L 27/156 (20130101); G09G
3/32 (20130101); G09G 3/2003 (20130101); H04N
5/642 (20130101) |
Current International
Class: |
H01L
27/15 (20060101); H04N 5/64 (20060101); G09G
3/20 (20060101); H01L 25/075 (20060101); G09G
3/32 (20160101) |
Field of
Search: |
;313/111,501,506
;345/55,76,204,80 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO-2010/111601 |
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Sep 2010 |
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WO |
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WO-2015/193434 |
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Dec 2015 |
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WO |
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WO-2016/030422 |
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Mar 2016 |
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WO |
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WO-2016/046283 |
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Mar 2016 |
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WO |
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WO-2017/042252 |
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Mar 2017 |
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WO |
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WO-2017/060487 |
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Apr 2017 |
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WO |
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WO-2017/149067 |
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Sep 2017 |
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WO |
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WO-2017/174632 |
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Oct 2017 |
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WO |
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Other References
Bower, C. A. et al., Transfer Printing: An Approach for Massively
Parallel Assembly of Microscale Devices, IEE, Electronic Components
and Technology Conference, (2008). cited by applicant .
Cok, R. S. et al., 60.3: AMOLED Displays Using Transfer-Printed
Integrated Circuits, Society for Information Display, 10:902-904,
(2010). cited by applicant .
Cok, R. S. et al., AMOLED displays with transfer-printed integrated
circuits, Journal of SID, 19(4):335-341 (2011). cited by applicant
.
Cok, R. S. et al., Inorganic light-emitting diode displays using
micro-transfer printing, Journal of the SID, 25(10):589-609,
(2017). cited by applicant .
Feng, X. et al., Competing Fracture in Kinetically Controlled
Transfer Printing, Langmuir, 23(25):12555-12560, (2007). cited by
applicant .
Gent, A.N., Adhesion and Strength of Viscoelastic Solids. Is There
a Relationship between Adhesion and Bulk Properties?, American
Chemical Society, Langmuir, 12(19):4492-4496, (1996). cited by
applicant .
Kim, Dae-Hyeong et al., Optimized Structural Designs for
Stretchable Silicon Integrated Circuits, Small, 5(24):2841-2847,
(2009). cited by applicant .
Kim, Dae-Hyeong et al., Stretchable and Foldable Silicon Integrated
Circuits, Science, 320:507-511, (2008). cited by applicant .
Kim, S. et al., Microstructural elastomeric surfaces with
reversible adhesion and examples of their use in deterministic
assembly by transfer printing, PNAS, 107(40):17095-17100 (2010).
cited by applicant .
Kim, T. et al., Kinetically controlled, adhesiveless transfer
printing using microstructured stamps, Applied Physics Letters,
94(11):113502-1-113502-3, (2009). cited by applicant .
Meitl, M. A. et al., Transfer printing by kinetic control of
adhesion to an elastomeric stamp, Nature Material, 5:33-38, (2006).
cited by applicant .
Michel, B. et al., Printing meets lithography: Soft approaches to
high-resolution patterning, J. Res. & Dev. 45(5):697-708,
(2001). cited by applicant .
Trindade, A.J. et al., Precision transfer printing of ultra-thin
AlInGaN micron-size light-emitting diodes, Crown, pp. 217-218,
(2012). cited by applicant .
Bower, C. A. et al., Micro-Transfer-Printing: Heterogeneous
Integration of Microscale Semiconductor Devices using Elastomer
Stamps, 2014 IEEE SENSORS, 3 pages and 1 page IEEE Xplore abstract,
date of conference: Nov. 2-5, 2014. cited by applicant.
|
Primary Examiner: Han; Jonathan
Attorney, Agent or Firm: Haulbrook; William R. Schmitt;
Michael D. Choate, Hall & Stewart LLP
Parent Case Text
PRIORITY APPLICATION
This application claims the benefit of U.S. Provisional Patent
Application No. 62/535,307, filed on Jul. 21, 2017, entitled
Micro-iLED Displays with Substrate Holes, the disclosure of which
is incorporated by reference herein in its entirety.
CROSS REFERENCE TO RELATED APPLICATION
Reference is made to U.S. patent application Ser. No. 14/754,573
filed May 21, 2015, titled Small-Aperture-Ratio Display with
Electrical Component, the disclosure of which is incorporated by
reference herein in its entirety.
Claims
What is claimed:
1. An inorganic light-emitting diode (iLED) display, comprising: a
display substrate having a display area and a shape defining open
holes extending through the display substrate in the display area,
wherein air can flow through the display substrate via the open
holes; and a plurality of inorganic light-emitting diodes (iLEDs)
disposed on, in, or over the display substrate in an array in the
display area, wherein at least some of the iLEDs are disposed
between at least some of the open holes in the display area and at
least some of the open holes are between at least some of the iLEDs
in the display area, wherein the plurality of iLEDs are operable to
emit light from the display and air moves through the open holes
when the plurality of iLEDs are operating to emit light from the
display.
2. The iLED display of claim 1, wherein the iLEDs emit light
through the display substrate.
3. The iLED display of claim 1, wherein the iLEDs emit light in a
direction away from the display substrate.
4. The iLED display of claim 1, wherein the open holes are at least
partially unfilled.
5. The iLED display of claim 1, comprising one or more audio
loudspeakers disposed adjacent to the display substrate and
disposed to emit sound through the open holes in the display
substrate.
6. The iLED display of claim 1, wherein the display substrate is
substantially rigid and comprising a flexible sheet laminated,
affixed, or adjacent to the display substrate.
7. The iLED display of claim 6, wherein the flexible sheet is
substantially black.
8. The iLED display of claim 7, comprising one or more audio
loudspeakers disposed adjacent to the flexible sheet with the
flexible sheet disposed between the display substrate and the one
or more audio loudspeakers.
9. The iLED display of claim 1, wherein an area of a convex hull
enclosing the plurality of iLEDs on the display substrate define
the display area of the display substrate and wherein the combined
area of the iLEDs is less than or equal to 25% of the display
area.
10. The iLED display of claim 1, wherein an area of a convex hull
enclosing the plurality of iLEDs on the display substrate define
the display area of the display substrate and wherein the open
holes cover more than or equal to 1% of the display area.
11. The iLED display of claim 1, wherein an area of a convex hull
enclosing the plurality of iLEDs on the display substrate define
the display area of the display substrate and wherein the open
holes form a regular array in the display area.
12. The iLED display of claim 1, comprising two or more electrical
conductors disposed on or over the display substrate and between
the open holes, each iLED electrically connected to two or more
electrical conductors.
13. The iLED display of claim 1, wherein the iLED display is a
matrix-addressed display comprising row-select and column-data
lines, and each iLED is controlled by a row-select line in
combination with a column-data line.
14. The iLED display of claim 13, wherein the iLED display is an
active-matrix display and comprises a controller disposed in, on,
or over the display substrate in association with one or more iLEDs
of the plurality of iLEDs and electrically connected to the one or
more iLEDs to control the one or more iLEDs using signals provided
by the row-select line and column-data line.
15. The iLED display of claim 1, comprising a plurality of pixels,
each pixel comprising one or more iLEDs of the plurality of iLEDs
and a pixel substrate on which the one or more iLEDs are disposed,
each pixel substrate disposed on the display substrate within the
display area.
16. The iLED display of claim 15, wherein each pixel substrate
comprises a broken or separated tether.
17. The iLED display of claim 1, wherein each iLED of the plurality
of iLEDs has a broken or separated tether.
18. The iLED display of claim 1, wherein each iLED of the plurality
of iLEDs has at least one of a width from 2 to 50 .mu.m, a length
from 2 to 50 .mu.m, and a thickness from 2 to 50 .mu.m.
19. The iLED display of claim 1, comprising a plurality of holes
between adjacent iLEDs of the plurality of iLEDs, between adjacent
pixels, or within an area bounded by pixels that does not include
any other pixels, in one or two dimensions parallel to a surface of
the display substrate.
20. The iLED display of claim 1, wherein the array is a regular
array.
21. An inorganic light-emitting diode (iLED) display, comprising: a
frame; a plurality of tile substrates mounted in the frame, the
tile substrates disposed in a common plane or on a common surface,
each tile substrate of the plurality of tile substrates comprising
a display area and one or more tile substrate edges, and wherein a
tile substrate edge of each tile substrate is disposed adjacent to
a tile substrate edge of another tile substrate; and a plurality of
inorganic light-emitting diodes (iLEDs) disposed on, in, or over
each tile substrate of the plurality of tile substrates in an array
in the display area, wherein at least one tile substrate of the
plurality of tile substrates has a shape that defines one or more
holes extending through the at least one tile substrate at the tile
substrate edge, wherein air can flow through the at least one tile
substrate via the one or more holes while the iLEDs are emitting
light.
22. The iLED display of claim 21, wherein the array is a regular
array.
23. An inorganic light-emitting diode (iLED) display, comprising: a
plurality of tile substrates disposed in a common plane or on a
common surface, each tile substrate of the plurality of tile
substrates comprising a display area and one or more tile substrate
edges, and wherein a tile substrate edge of each tile substrate is
disposed adjacent to a tile substrate edge of another tile
substrate; a plurality of inorganic light-emitting diodes (iLEDs)
disposed on, in, or over each tile substrate of the plurality of
tile substrates in an array in the display area; and at least one
tile substrate of the plurality of tile substrates has a shape that
defines one or more holes extending through the at least one tile
substrate at the adjacent tile substrate edge of the at least one
tile substrate of the plurality of tile substrates, wherein two
adjacent tile substrates of the plurality of tile substrates having
adjacent display substrate edges each have shape that defines at
least one hole extending through the tile substrate at the display
substrate edge and wherein at least one of the at least one hole of
each of the adjacent tile substrates overlap to form a larger
hole.
24. An inorganic light-emitting diode (iLED) display, comprising: a
display substrate having a display area and a shape defining holes
extending through the display substrate in the display area; a
plurality of inorganic light-emitting diodes (iLEDs) disposed on,
in, or over the display substrate in an array in the display area;
and wherein at least some of the iLEDs are disposed between at
least some of the holes in the display area and at least some of
the holes are between at least some of the iLEDs in the display
area, and wherein one hole of the holes is disposed between each
pair of adjacent pixels in one or two dimensions parallel to a
surface of the display substrate, each of the adjacent pixels
comprising one or more of the iLEDs.
25. An inorganic light-emitting diode (iLED) display, comprising: a
display substrate having a display area and a shape defining holes
extending through the display substrate in the display area,
wherein air can flow through the display substrate via the holes
and foam is disposed in the holes; and a plurality of inorganic
light-emitting diodes (iLEDs) disposed on, in, or over the display
substrate in an array in the display area, wherein at least some of
the iLEDs are disposed between at least some of the holes in the
display area and at least some of the holes are between at least
some of the iLEDs in the display area.
26. The iLED display of claim 25, wherein the foam is substantially
black.
27. An inorganic light-emitting diode (iLED) display, comprising: a
frame; a plurality of tiles mounted in the frame, each of the
plurality of tiles comprising a tile substrate comprising a display
area and having a shape defining one or more holes extending
through the tile substrate in the display area; and a plurality of
inorganic light-emitting diodes (iLEDs) disposed on, in, or over
the tile substrate for each of the plurality of tiles, wherein at
least some of the iLEDs of the tiles are disposed between at least
some of the holes of the tiles and at least some of the holes of
the tiles are between at least some of the iLEDs of the tiles.
28. An inorganic light-emitting diode (iLED) display, comprising: a
display substrate having a display area and a shape defining holes
extending through the display substrate in the display area,
wherein air can flow through the display substrate via the holes;
and a plurality of inorganic light-emitting diodes (iLEDs) disposed
on, in, or over the display substrate in an array in the display
area, wherein at least some of the iLEDs are disposed between at
least some of the holes in the display area and at least some of
the holes are between at least some of the iLEDs in the display
area, wherein the plurality of iLEDs are operable to emit light
from the display, and wherein an area of a convex hull enclosing
the plurality of iLEDs on the display substrate defines the display
area of the display substrate and the holes cover more than or
equal to 25% of the display area.
Description
TECHNICAL FIELD
The present invention relates generally to direct-view inorganic
iLED displays having a small aperture ratio.
BACKGROUND
Flat-panel direct-view displays are widely used in conjunction with
computing devices, in portable devices, and for entertainment
devices such as televisions. Such displays typically employ a
plurality of pixels distributed over a display substrate to display
images, graphics, or text. In a color display, each pixel includes
light emitters that emit light of different colors, such as red,
green, and blue. For example, liquid crystal (LC) displays employ
liquid crystals to block or transmit light from a backlight behind
the liquid crystals and organic light-emitting diode (OLED)
displays rely on passing current through a layer of organic
material that glows in response to the current. Alternatively,
front- or rear-projection display technologies project images onto
a reflective or transmissive display screen, respectively.
Inorganic light-emitting diodes (iLEDs) can also be used in
displays, including very large displays. For example a 10.3 meter
4k-resolution iLED display has been commercially installed in a
cinema by Samsung, although conventional movie theater screens tend
to be at least 13 meters in size.
Most direct-view flat-panel displays use either passive-matrix (PM)
control employing electronic circuitry external to the display
substrate or active-matrix (AM) control employing electronic
circuitry formed directly on the display substrate and associated
with each light-emitting element. Both OLED and LC displays using
both passive-matrix control and active-matrix control are
commercially available. An example of such an AMOLED display device
is disclosed in U.S. Pat. No. 5,550,066.
Typical systems for both direct-view and projected displays include
audio equipment for emitting sound; generally, the sound emitted
corresponds to the displayed images, for example a sound track that
accompanies a video stream, such as a film. The audio equipment is
usually provided separately from the display, for example on the
sides, beneath, above, or remotely from the display. In theaters,
audio loudspeakers are additionally located behind a reflective
display screen, which contributes to the verisimilitude of the
audio-visual experience by locating the source of sound more
closely to the images from which the sound purportedly comes.
However, the display substrate in direct-view displays interferes
with sound from audio loudspeakers located behind the display
substrate, inhibiting the use of such direct-view displays in
theaters.
The amount of light emitted from a liquid crystal display is
determined by the brightness of the backlight, the transmissivity
of the liquid crystals, and the pixel area of the display through
which light is emitted (the fill factor or aperture ratio). A
larger pixel area for a given display will transmit more light than
a smaller pixel area for the same display. Hence, in order to
achieve a desirably bright LCD, the pixels are preferably large.
For an OLED display, the brightness depends on the current density
passed through the OLED pixels. At higher current densities,
brightness is increased and lifetime is decreased. Thus, a larger
light-emitting OLED pixel area will increase the lifetime of an
OLED display by reducing the current density. It is therefore also
preferred that OLED pixels are large. Thus, for conventional
direct-view flat-panel displays, such as liquid crystal (LC) or
organic light-emitting diode (OLED) displays, a larger aperture
ratio typically results in a longer lifetime, a greater maximum
brightness, or both longer lifetime and greater maximum brightness
for a flat-panel direct-view display, inhibiting the inclusion of
other features or functions on the display substrate.
Inorganic light-emitting diode displays using micro-LEDs (for
example having an area less than 1 mm square, less than 100 microns
square, or less than 50 microns square or having an area small
enough that it is not visible to an unaided observer of the display
at a designed viewing distance) are also known. For example, U.S.
Pat. No. 8,722,458 entitled Optical Systems Fabricated by
Printing-Based Assembly teaches transferring light-emitting,
light-sensing, or light-collecting semiconductor elements from a
wafer substrate to a destination substrate.
Tiled displays are used to make displays that are larger than can
be made on a single substrate. For example, U.S. Pat. Nos.
6,881,946, 7,394,194, 7,408,296, and 9,590,025 disclose various
direct-view tiled displays. U.S. Patent Application Publication No.
2002/0118321 discloses a tiled LCD display. In 2017, Sony
Corporation demonstrated a 32 feet by 9 feet tiled iLED display
with 16-inch by 18-inch modules (the Sony Canvas).
Flat-panel displays consume energy and produce heat. Some display
designs incorporate features for cooling the display with either
active or passive structures. U.S. Pat. No. 7,157,838 discloses an
electroluminescent display on a substrate with drive circuitry and
a cooling channel defined behind the substrate adjacent to the
drive circuitry.
There remains a need for display systems, structures, and methods
of manufacturing that provide increased lifetime, brightness, image
quality, ease of manufacturing, reduced cost and improved
functionality and utility in simpler and more robust structures and
for more applications.
SUMMARY
According to certain embodiments of the present invention, an
inorganic light emitter such as a micro inorganic light-emitting
diode (micro-iLED) provides high-brightness light (for example,
having an efficiency or brightness greater than incandescent,
fluorescent, or OLED light emitters) output without requiring
relatively large light-controlling pixel areas or organic
materials, and without restrictions on viewing angle. Light
emitters formed in a crystalline semiconductor wafer using
conventional materials and processes can be micro-transfer printed
to a display substrate at a relatively low cost and with excellent
efficiency. Therefore, among other things, certain embodiments of
the present invention provide increased lifetime, image quality,
ease of manufacturing, and reduced cost and improved functionality
and utility in a simpler and more robust display structure for a
variety of applications. Micro-iLEDs printed onto a display
substrate, for example, using micro-transfer printing occupy
relatively little area on the display substrate, providing space to
construct or otherwise provide additional structures, circuits, or
devices on the display substrate, such as holes to allow sound to
pass through the display substrate. Certain embodiments of the
present invention enable a direct-view display with audio speakers
located behind the display substrate and improved audio sound
reproduction to a viewer and listener in front of the display as
well as improved cooling and reduced weight.
According to certain embodiments of the present invention, an
inorganic light-emitting diode (iLED) display comprises a display
substrate having a display area and a shape defining one or more
holes extending through the display substrate in the display area.
A plurality of inorganic light-emitting diodes (iLEDs) are disposed
on, in, or over the display substrate in a regular array in the
display area. At least some of the iLEDs are disposed between at
least some of the one or more holes in the display area and at
least some of the one or more holes are between at least some of
the iLEDs in the display area.
In some embodiments, the iLED display comprises a plurality of
tiles, each tile comprising a display substrate comprising a
display area and one or more holes extending through the display
substrate in the display area of the tile. At least some of the
iLEDs are disposed between at least some of the one or more holes
in the display area of the tile and at least some of the one or
more holes are between at least some of the iLEDs in the display
area of the tile.
In some embodiments, the iLEDs emit light through the display
substrate. In some embodiments, the iLEDs emit light in a direction
away from the display substrate.
In some embodiments, the one or more holes are at least partially
unfilled. In some embodiments, the display comprises foam disposed
in the one or more holes (e.g., the one or more holes are at least
partially filled with foam), for example a substantially black
foam.
In some embodiments, one or more audio loudspeakers are disposed
adjacent to the display substrate and configured to emit sound
through the one or more holes in the display substrate. The display
substrate can be substantially rigid and the iLED display can
comprise a flexible sheet, such as a substantially black sheet,
laminated, affixed, or adjacent to the display substrate. The one
or more audio loudspeakers can be disposed adjacent to the flexible
sheet with the flexible sheet disposed between the display
substrate and the one or more audio loudspeakers.
In some embodiments of the present invention, the plurality of
iLEDs on the display substrate define a minimum contiguous convex
display area of the display substrate that includes all of the
iLEDs and the combined area of the iLEDs is less than or equal to
25%, 10%, 5%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the minimum
contiguous convex display area. The one or more holes can cover
more than or equal to 25%, 12.5%, 10%, 5%, 2%, or 1% of the minimum
contiguous convex display area.
In some embodiments, the iLED display comprises two or more
electrical conductors disposed on or over the display substrate and
between the one or more holes in the display area, each iLED
electrically connected to two or more electrical conductors.
In some embodiments, the iLED display is a matrix-addressed display
having row-select and column-data lines, and each iLED is
controlled by a row-select line in combination with a column-data
line. In some embodiments, the iLED display is an active-matrix
display and a controller, for example a pixel controller, is
disposed in, on, or over the display substrate in the display area
in association with one or more iLEDs and electrically connected to
the one or more iLEDs to control the one or more iLEDs using select
and data signals provided by the row-select line and column-data
line, respectively.
In certain embodiments, light-emitting diodes are organized into
pixels and the plurality of pixels forms a regular array on the
display substrate or are irregularly or randomly arranged. The
light-emitting diodes can be inorganic light-emitting diodes
(iLEDs) or micro-inorganic-light-emitting diodes (micro-iLEDs).
Each pixel can comprise one or more iLEDs. In certain embodiments,
each pixel includes a single light emitter. In certain embodiments,
each pixel includes at least three light emitters, each of the at
least three light emitters emitting light of different colors. In
some embodiments, the one or more light emitters are disposed on a
display substrate. In some embodiments, the one or more light
emitters are disposed on a pixel substrate and each pixel substrate
is disposed on the display substrate. Each pixel substrate can
comprise a broken or separated tether as a consequence of
micro-transfer printing the pixel substrate. In some embodiments,
each iLED of the plurality of iLEDs comprises a broken or separated
tether as a consequence of micro-transfer printing the iLEDs.
In certain embodiments of the present invention, each iLED of the
plurality of iLEDs has at least one of a width from 2 to 50 .mu.m
(e.g., 2 to 5 .mu.m, 5 to 10 .mu.m, 10 to 20 .mu.m, or 20 to 50
.mu.m), a length from 2 to 50 .mu.m (e.g., 2 to 5 .mu.m, 5 to 10
.mu.m, 10 to 20 .mu.m, or 20 to 50 .mu.m), and a thickness from 2
to 50 .mu.m (e.g., 2 to 5 .mu.m, 5 to 10 .mu.m, 10 to 20 .mu.m, or
20 to 50 .mu.m).
In some embodiments of the present invention, the iLED display
comprises a plurality of holes between adjacent iLEDs of the
plurality of iLEDs, between adjacent pixels, or within an area
bounded by pixels that does not include any other pixels, in one or
two dimensions parallel to a surface of the display substrate.
In certain embodiments, the one or more light emitters are formed
in or on or located on the display substrate. In certain
embodiments, each light emitter is formed in or on or disposed on a
pixel substrate separate from the display substrate. In certain
embodiments, each pixel includes a pixel substrate and the display
includes a plurality of pixel substrates disposed on the display
substrate. A single iLED, or multiple iLEDs can be disposed on each
pixel substrate. In some embodiments, multiple pixels share a
common pixel substrate.
In certain embodiments, each pixel includes a pixel controller and
the pixel controller is electrically connected to the one or more
light emitters in the pixel to control the light output by the one
or more light emitters. In some embodiments, the pixel controller
is located on the display substrate. In other embodiments, a pixel
includes a pixel substrate separate from the display substrate and
the pixel controller is located on the pixel substrate.
In certain embodiments, one or more electrical conductors such as
conductive wires electrically connect two or more of the pixels in
the display area. In certain embodiments, the one or more
electrical conductors conduct signals for controlling the pixels,
for conducting power to the pixels, or for providing a ground
reference voltage.
In certain embodiments, the combined light-emissive areas of the
light emitters or the combined areas of the light emitters is less
than or equal to one eighth, one tenth, one twentieth, one
fiftieth, one hundredth, one five-hundredth, one thousandth, one
two-thousandth, or one ten-thousandth of the minimum contiguous
convex display substrate area.
In certain embodiments, the display substrate is at least one of
plastic, glass, and sapphire. In certain embodiments, the display
substrate is transparent to visible light. In certain embodiments,
the display substrate is at least partially transparent to visible
light. In certain embodiments, the iLED display has no less than 30
percent transparency to visible light (e.g., no less than 50%, 80%,
90%, or 95% transparency to visible light).
In certain embodiments, each pixel includes: a printed pixel of a
plurality of printed pixels disposed on the display substrate, each
printed pixel of the plurality of printed pixels including: a pixel
substrate of a plurality of pixel substrates on which the micro
inorganic light-emitting diodes for a respective pixel are
disposed, and a fine interconnection having a width of 100 nm to 1
.mu.m electrically connected to the micro inorganic light-emitting
diodes for the respective pixel.
In certain embodiments, the display substrate includes one or more
crude lithography interconnections having a width from 2 .mu.m to 2
mm, wherein each crude lithography interconnection is electrically
connected to at least one of the plurality of pixels on the display
substrate. The crude lithography interconnections can be disposed
at least partly or entirely on the display substrate.
In certain embodiments, the plurality of light emitters includes a
plurality of yellow printed micro inorganic light-emitting diodes
that emit yellow light, and wherein each pixel of the plurality of
pixels includes a yellow printed micro inorganic light-emitting
diode of the plurality of yellow printed micro inorganic
light-emitting diodes that emit yellow light.
The disclosed technology includes a method of micro assembling an
inorganic light-emitting diode (iLED) display, the method
including: forming a plurality of printable inorganic micro LEDs on
one or more native source wafers; and micro transfer printing the
plurality of printable micro-iLEDs onto a non-native substrate to
form one or more pixels. One or more printable micro-iLEDs can be
micro-transfer printed onto a non-native pixel substrate to form a
pixel and the pixels can be micro-transfer printed onto a
non-native display substrate. Alternatively, a plurality of
printable micro-iLEDs can be micro-transfer printed onto a
non-native display substrate to form a plurality of pixels on the
display substrate.
The plurality of micro-transfer printable micro inorganic LEDs can
include: one or more red printed micro inorganic light-emitting
diodes that emit red light; one or more green printed micro
inorganic light-emitting diodes that emit green light; and one or
more blue printed micro inorganic light-emitting diodes that emit
blue light. Each pixel can include a red printed micro inorganic
light-emitting diode of the plurality of red printed micro
inorganic light-emitting diodes, a green printed micro inorganic
light-emitting diode of the plurality of green printed micro
inorganic light-emitting diodes, and a blue printed micro inorganic
light-emitting diode of the plurality of blue printed micro
inorganic light-emitting diodes.
In certain embodiments, all of the pixels are substantially
identical.
In some embodiments, the display substrate is a tile substrate.
In some embodiments, an inorganic light-emitting diode (iLED)
display comprises a plurality of tile substrates disposed in a
common plane or on a common surface, each tile substrate of the
plurality of tile substrates comprising a display area and one or
more tile substrate edges, and wherein a tile substrate edge of
each tile substrate is disposed adjacent to a tile substrate edge
of another tile substrate; a plurality of inorganic light-emitting
diodes (iLEDs) disposed on, in, or over each tile substrate of the
plurality of tile substrates in an array in the display area; and
at least one tile substrate of the plurality of tile substrates has
a shape that defines one or more holes extending through the at
least one tile substrate at the adjacent tile substrate edge of the
at least one tile substrate of the plurality of tile
substrates.
In some embodiments, two adjacent tile substrates of the plurality
of tile substrates having adjacent display substrate edges each
have shape that defines at least one hole extending through the
tile substrate at the display substrate edge and wherein at least
one of the at least one hole of each of the adjacent tile
substrates overlap to form a larger hole. In some embodiments, the
array is a regular array.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, aspects, features, and advantages
of the present disclosure will become more apparent and better
understood by referring to the following description taken in
conjunction with the accompanying drawings, in which:
FIGS. 1 and 2 are perspective illustrations of displays/tiles
according to illustrative embodiments of the present invention;
FIG. 3 is a schematic of a pixel, according to illustrative
embodiments of the present invention;
FIGS. 4 and 5 are cross sections of displays/tiles, according to
illustrative embodiments of the present invention;
FIG. 6 is a perspective illustration of a displays made of tiles
according to illustrative embodiments of the present invention;
FIG. 7 is a cross section of a display, according to illustrative
embodiments of the present invention;
FIG. 8 is a perspective illustration of a display having pixel
substrates, according to illustrative embodiments of the present
invention; and
FIG. 9 is a perspective illustration of a display including pixels
that each have a pixel controller, according to illustrative
embodiments of the present invention;
FIG. 10A is a perspective illustration of a pixel with a separate
pixel controller and pixel substrate corresponding to FIG. 9,
according to illustrative embodiments of the present invention;
FIG. 10B is a perspective illustration of a pixel with a pixel
control circuit formed in or on a pixel substrate, according to
illustrative embodiments of the present invention;
FIG. 11 is a perspective illustration of an illustrative embodiment
of the present invention corresponding to FIG. 10A;
FIGS. 12A and 12B are illustrative cross sections of horizontal
LEDs, according to illustrative embodiments of the present
invention; and
FIG. 13 is a perspective illustration of a display, according to
illustrative embodiments of the present invention.
The features and advantages of the present disclosure will become
more apparent from the detailed description set forth below when
taken in conjunction with the drawings, in which like reference
characters identify corresponding elements throughout. In the
drawings, like reference numbers generally indicate identical,
functionally similar, and/or structurally similar elements. The
figures are not drawn to scale since the variation in size of
various elements in the Figures is too great to permit depiction to
scale.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
Certain embodiments of the present invention comprise a direct-view
flat-panel display 99 provided on a display substrate 10 that
incorporates holes 30 in the display substrate 10. A display
substrate 10 can be a tile substrate 16 in a tiled display. As used
herein, a substrate (e.g., a display substrate 10 or tile substrate
16) that "incorporates" one or more holes 30 (or is alternatively
described as "having" or "comprising" one or more holes 30) is a
substrate that has a shape that defines one or more holes. Holes 30
can allow air movement through a display 99 and enable audio
devices such as audio loudspeakers 36 to be located behind the
display 99 with respect to a display viewer and provide sound
transmission through the holes 30 and improved audio reproduction
for the display viewer. In certain embodiments, holes also improve
display cooling by improving airflow over and through a display
substrate 10. Holes 30 can reduce the overall extent or size of a
display system 99 by locating the audio devices (loudspeakers or
microphones) behind the display. Holes in a display system 99 can
also reduce the wind resistance of the display system when located
outdoors and exposed to wind, as well as reduce weight. A reduced
weight is helpful when mounting large number of tiles in a frame,
for example a vertical frame.
Referring to the perspective of FIG. 1, an inorganic light-emitting
diode (iLED) display 99 comprises a display substrate 10 comprising
a display area 12 and one or more holes 30 extending through the
display substrate 10 in the display area 12. Holes 30 can be
located in a regular array, or not. Holes 30 can have circular,
round, oval, polygonal (e.g., square or hexagonal) or similar cross
section and can be regular or irregular. A plurality of inorganic
light-emitting diodes (iLEDs) 22 are disposed on, in, or over the
display substrate 10 in an array in the display area 12 and groups
of iLEDs 22 can be arranged in pixels 20 in the display area 12 of
the display substrate 10. As used herein, a display area 12 is the
minimum contiguous area over a display substrate 10 that is the
smallest area that includes all of the iLEDs 22 in pixels 20 in a
convex shape, such as a polygon with no concave external angles
(mathematically, such an area is a convex hull). In certain
embodiments, an array is a regular array. As used herein, a regular
array is a two-dimensional array in which pixels 20 are separated
by a common pixel pitch in each dimension in the array. Different
rows or columns of pixels 20 in a regular array can have different
spatial phases or are offset with respect to each other. In certain
embodiments, the iLED display 99 of FIG. 1 is used as a tile 14 in
a larger tiled display so that each display substrate 10 is a tile
substrate 16 (e.g., as shown in FIG. 6).
In various embodiments of the present invention, at least some of
the iLEDs 22 or pixels 20 are located between adjacent holes 30 in
the display area 12 of a display substrate 10 in one or two
dimensions parallel to a surface of the display substrate 10. In
certain embodiments, at least some of the iLEDs 22 or pixels 20 are
electrically connected to power, ground, and control signals
provided on electrical conductors 24. At least some of the holes 30
can be located between at least some of the iLEDs 22 or adjacent
pixels 20 in a display area 12 of a display substrate 10 so that
the holes 30 and iLEDs 22 or pixels 20 are interspersed in the
display area 12 of the display substrate 10. In some embodiments
(such as the illustrative embodiment shown in FIG. 2), an iLED
display 99 comprises a plurality of holes 30 between adjacent iLEDs
22 or adjacent pixels 20 of a plurality of iLEDs 22 in one or two
dimensions parallel to a surface of a display substrate 10. As used
herein, two iLEDs 22 are adjacent if no other iLEDs 22 are between
the adjacent iLEDs 22; two pixels 20 are adjacent if no other
pixels 20 are between the adjacent pixels 20; and two holes 30 are
adjacent if no other holes 30 are between the adjacent holes 30. On
a two-dimensional surface such as a surface of a display substrate
10 or tile substrate 16, a pixel 20 or hole 30 can be adjacent to
multiple pixels 20 or holes 30, respectively, if no other pixels 20
or holes 30 are enclosed within a convex hull surrounding the
adjacent pixels 20 or holes 30. As used herein, an iLED 22 or hole
30 is between two other objects if a line segment that intersects
the two other objects also intersects the iLED 22 or hole 30.
Additionally, an iLED 22 or hole 30 is between three or more other
objects if a convex hull that encloses the three other objects also
encloses at least a portion of the iLED 22 or hole 30.
In some embodiments, iLEDs 22 are matrix addressed and controlled
through two or more electrical conductors 24, for example
electrical conductors 24 that can be row-select lines and
column-data lines. The two or more electrical conductors 24 can be
disposed on or over a display substrate 10 and between at least
some of the holes 30, for example in a substantially rectilinear
array at least partially in the display area 12 of the display
substrate 10. Alternatively, electrical conductors 24 can be routed
around holes 30 in a display area 12.
In some embodiments of the present invention, iLEDs 22 can emit
light 60 in a direction opposite to or away from a display
substrate 10 so that most or all of the light emitted does not pass
or is not transmitted through the display substrate 10 (in a
top-emitter configuration). Referring to FIG. 12A, a micro-transfer
printed horizontal LED structure comprises an iLED 22
micro-transfer printed on or over a reflective layer 48 on a
display substrate 10. Each iLED 22 has two or more iLED contact
pads 40 exposed through patterned protective transparent dielectric
structures 46 and electrically connected to display substrate
contact pads 44 on the display substrate 10 with electrodes 42.
Light 60 is emitted from the top side of the iLED 22 when
electrical current is provided through the display substrate
contact pads 44, electrodes 42, and iLED contact pads 40. U.S. Pat.
No. 6,825,559 describes methods of making micro-transfer-printable
iLEDs 22 useful in making certain embodiments disclosed herein.
As shown in the perspective of FIG. 2, a plurality of holes 30 can
be located between iLEDs 22 or pixels 20, or within a portion of a
display area 12 of a display substrate 10 bounded by pixels 20 that
does not include any pixels 20, in one or both dimensions (x and y)
over and in a direction parallel to the display substrate 10 in the
display area 12. By having more and smaller holes 30 in a display
substrate 10, the rigidity or mechanical strength, or robustness of
an iLED display 99 can be improved. As is also illustrated in FIG.
2, light 60 can be emitted from the iLEDs 22 through the display
substrate 10 (in a bottom-emitter configuration), in contrast to
the top-emitter embodiments shown in FIG. 1. The illustrative
embodiments shown in FIG. 1 and FIG. 2 can be modified to be either
top-emitter or bottom-emitter iLED displays 99. Referring to FIG.
12B, a micro-transfer printed iLED structure comprises an iLED 22
micro-transfer printed on the display substrate 10. Each iLED 22
has two or more iLED contact pads 40 exposed through protective
dielectric structures 46 and electrically connected to display
substrate contact pads 44 on the display substrate 10 with
reflective electrodes 42. Light 60 is emitted from the bottom side
of the iLED 22 through the display substrate 10 when electrical
current is provided through the display substrate contact pads 44,
electrodes 42, and iLED contact pads 40.
Referring also to the plan view illustration of FIG. 3, iLEDs 22
can be organized and controlled in groups of pixels 20, each of
which comprises one or more iLEDs 22. The iLEDs 22 in a pixel 20
can include iLEDs 22 that emit different colors of light, for
example red light from a red-light emitter 22R, green light from a
green-light emitter 22G, and blue light from a blue-light emitter
22B (collectively iLEDs 22). As shown in the exemplary embodiments
of FIGS. 1-3, pixels 20 and iLEDs 22 in pixels 20 can be
electrically controlled to emit light 60 using electrical
conductors 24, for example row-select conductors 24 and column-data
conductors 24 in a matrix-addressed control scheme for the pixels
20. In certain embodiments, conductors 24 are provided in two metal
layers on or in a display substrate 10 to avoid electrical short
circuits and can be electrically connected to display substrate
contact pads 44 (e.g., as shown in FIGS. 12A, 12B). Other
electrical connections suitable for connecting to display control
circuits (not shown) can be used. For example, in certain
embodiments, conductors are provided in a single metal layer and
jumpers are used to provide complete electrical connections without
causing electrical shorts. In some embodiments, row- or
column-control circuits can be provided on a display substrate 10,
for example around the periphery of the display substrate 10 and
external to the display area 12 (as discussed further with respect
to FIG. 5 below).
FIG. 4 illustrates a partial cross section of an iLED display 99
across a horizontal conductor 24 with pixel 20 iLEDs 22, conductors
24 (in two layers) and holes 30 (indicated with dashed lines) on a
display substrate 10. The holes 30 can form a regular array in the
minimum contiguous convex display area 12. Alternatively, the holes
30 can be located in a random arrangement. According to some
embodiments of the present invention, air can flow through holes 30
in a display substrate 10 to cool micro-iLEDs 22. Holes 30 in an
iLED display 99 can improve utilization of various cooling schemes
for the associated viewing space as well as the iLED display 99.
For example, forcing air in either direction through a display
substrate 10 from the rear (a side of the display substrate 10
opposite a viewer of the iLED display 99) would improve cooling of
display-related components behind the iLED display 99. Holes 30 can
also be used to allow at least some of the air in a room to flow
through an iLED display 99, thereby reducing the iLED display 99
impact on existing air conditioning and heating systems in a given
room in which the iLED display 99 is placed. In contrast, a typical
illuminating display of the prior art completely blocks flow in a
direction normal to a surface of its display substrate.
In some applications of certain embodiments of the present
invention, an iLED display 99 is placed in a dark room to improve
the contrast of the iLED display 99, for example a theater. In
other applications of certain embodiments of the present invention,
an iLED display 99 is placed in a location with significant and
noticeable ambient light, for example a commercial advertising
venue, either indoor or outdoor. In either case, it can be helpful
for the iLED display 99 to be relatively bright to observers. Since
micro-iLEDs 22 are never perfectly efficient, they will generate
heat in addition to light and cooling supplied to the micro-iLEDs
22 can improve their performance and lifetime. Cooling can be
supplied, for example, by providing airflow over micro-LEDs 22 and
through holes 30.
In certain embodiments, and as shown in the illustrative
embodiments of FIGS. 1-4, holes 30 are at least partially unfilled
(e.g., are completely and entirely empty). In some embodiments,
referring to FIG. 5, holes 30 are at least partially filled with a
foam 32. As used herein, a foam 32 is a material comprising both a
solid and a gas, such as air. Foam 32 can comprise more than 50%,
70%, 80, or 90% gas. The solid can be flexible, for example a
flexible plastic, can be substantially light-absorbing or black,
for example absorbing more than or equal to 50%, 60%, 70%, 80%,
90%, or 95% of incident visible light, and can be either
closed-cell or open-cell. Foam 32 can be a foam rubber or analogous
material, for example the foam earpieces found on headphones or ear
buds. Foam 32 can be flexible and can be designed to efficiently
transmit sound.
FIG. 5 also illustrates a micro-control structure for rows or
columns of pixels 20 on a display substrate 10. As shown in FIG. 5,
a row- or column-control circuit 70 is disposed on a side of the
display substrate 10 opposite the iLEDs 22 (on the other side of
display substrate 10 from the iLEDs 22). The row- or column-control
circuit 70 can control rows or columns of pixels 20, for example by
providing row-select signals or column-data signals to the pixels
20 or iLEDs 22 in the iLED display 99 through conductors 24, for
example in a passive-matrix control scheme for the iLED display 99.
The row- or column-control circuit 70 can be electrically connected
to the iLEDs 22 through vias 80, for example vias 80 filled with an
electrically conductive material. As the row- or column-control
circuit 70 is disposed on the opposite side of the display
substrate 10, it can be located within the display area 12 in a
top-emitter configuration (corresponding to FIG. 1, not shown in
FIG. 5).
In some embodiments of the present invention, and as shown in FIG.
6, an iLED display 99 is a tiled iLED display 99 comprising a
plurality of tiles 14 each comprising a tile substrate 16. A tile
substrate 16 can be a display substrate 10 or a display substrate
10 can be a tile substrate 16. Each tile substrate 16 comprises one
or more holes 30 extending through the tile substrate 16 in the
display area 12. The display area 12 can also include all of the
iLEDs 22 on all of the tile substrates 16 of the iLED display 99.
iLEDs 22 are distributed over the tile substrate 16 between holes
30 and holes 30 are distributed between the iLEDs 22 or pixels 20
of the display area 12. In certain embodiments, each tile 14 is
managed as a separate display with tile control circuits
controlling each tile 14 under the supervision of a display
controller or the tiles 14 can be electrically connected to form
larger arrays of pixels 20 that are controlled as a larger group by
a display controller.
A tile structure can correspond to a display structure. Thus, the
illustrations of FIGS. 1, 2, 4, and 5 can also refer to tiles 14.
Display substrates 10 can be tile substrates 16, each having an
array of pixels 20 and iLEDs 22, and can include a row- or
column-control circuit 70 for each tile 14. The tiles 14 can be
under the control of a display controller providing display signals
to the row- or column-control circuits 70 for each tile 14. In
particular, for a top-emitter configuration, a display controller
and printed circuit board for mounting the tiles 14 can be provided
and connected to the tiles 14 on the side of the tiles 14 opposite
the iLEDs 22. In some embodiments of the present invention, holes
30 are located between or on the edges 18 of tile substrates 16. In
this context, a hole 30 can be a notch or other indentation in the
tile substrate 16 that extends through the tile substrate 16. In
some embodiments, corresponding semicircular or rectangular holes
30 can be located on adjacent tile substrate edges 18 to form a
larger hole 30 (as shown in FIG. 13).
Referring to FIG. 7, in some embodiments of the present invention,
an iLED display 99 comprises one or more audio loudspeakers 36
(e.g., an electro-acoustic transducer that converts electrical
audio signals into sound) disposed adjacent to a display substrate
10 and configured to emit sound through holes 30 in the display
substrate 10 (or tile substrates 16). In this way, the sound for a
video sequence displayed by the array of pixels 20 can appear to
more closely originate from the images displayed in the video
sequence, improving the verisimilitude of an audio-visual
experience. This is particularly useful for theater settings in
which the display screens are relatively large, for example greater
than or equal to two, five, ten, fifteen, twenty, or fifty meters
in diagonal, and for large audiences, for example greater than or
equal to two, five, ten, or twenty-five people.
In some embodiments of the present invention, a display substrate
10 is substantially rigid and an iLED display 99 comprises a
flexible sheet 34 laminated or affixed to the display substrate 10,
or the flexible sheet 34 is disposed adjacent to the display
substrate 10. By substantially rigid is meant that the display
substrate 10 does not derive any benefit from being flexed, is not
intentionally flexed, or that the display substrate 10 does not
intentionally transmit sound or is not a primary means for sound
transmission. Rather, holes 30 can be the primary means for sound
transmission. The flexible sheet 34 can be substantially black. In
some embodiments, the flexible sheet 34 is disposed between the
display substrate 10 and the audio loudspeaker 36. In some
embodiments of the present invention, a flexible sheet 34 flexes in
response to sound and effectively transmits sound. Furthermore, a
flexible sheet 34 can be made of a cloth, for example a cloth
having a relatively open weave, through which air can readily pass,
improving sound transmission and cooling of an iLED display 99.
The use of black materials can enhance the contrast of an iLED
display 99 by absorbing stray light emitted by iLEDs 22 or
absorbing ambient light. Display substrates 10 can also include
black materials, coatings, or layers to improve contrast.
Holes 30 can be sized, shaped, or spaced to optimize audio
throughput through a display substrate 10 and to reduce unwanted
effects such as audio reflections and distortion, especially for
mid-range frequencies important for understanding human speech or
dialog found in films or movies, for example in a theater. For
example, hole 30 edges can be rounded and the holes 30
substantially circular. Holes 30 can also have a size matched to
the size of audio loudspeakers 36 (for example audio loudspeakers
36 having a diameter equal to or less than the diameter of a
corresponding hole 30) and one or more of the audio loudspeakers 36
can be located directly behind or adjacent to the holes 30, so that
sound emitted by the one or more of the audio loudspeakers 36
passes substantially (e.g., more than 25%, 50%, or 75%) through the
holes 30. Likewise, in certain embodiments, microphones located
behind a display substrate 10 can be disposed in or directly behind
holes 30 to improve reception of audio signals through the display
substrate 10 by the microphones and the microphones can have a size
matched to the holes 30, for example having a size or diameter
equal to or smaller than the holes 30.
Certain embodiments of the present invention comprise LED
light-emitters, for example micro-iLEDs 22, that enable a
relatively small aperture ratio, leaving space on the display
substrate 10 or tile substrate 16 for the holes 30 through which
sound can pass relatively unimpeded. In some embodiments, each iLED
22 of the plurality of iLEDs 22 has at least one of a width from 2
to 50 .mu.m (e.g., 2 to 5 .mu.m, 5 to 10 .mu.m, 10 to 20 .mu.m, or
20 to 50 .mu.m), a length from 2 to 50 .mu.m (e.g., 2 to 5 .mu.m, 5
to 10 .mu.m, 10 to 20 .mu.m, or 20 to 50 .mu.m), and a thickness
from 2 to 50 .mu.m (e.g., 2 to 5 .mu.m, 5 to 10 .mu.m, 10 to 20
.mu.m, or 20 to 50 .mu.m).
In various embodiments, the combined area of the light-emitting
area of the iLEDs 22 or the iLEDs 22 themselves is less than or
equal to 25%, 10%, 5%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the
minimum contiguous convex display area 12 including all of the
iLEDs 22 on a display substrate 10. For example, micro-iLEDs 22
have been constructed having a size of 8.times.15 microns and area
of 120 .mu.m.sup.2. For example, a 4k.times.2k full color display
can have 4096.times.2048.times.3 iLEDs 22 (each having an area of
120 .mu.m.sup.2) equaling a total iLED 22 area of 3020 mm.sup.2. An
iLED display 99 having a display substrate 10 one meter high by two
meters long has an area of two square meters or 2,000,000 mm.sup.2,
so that only 3020/2,000,000=0.15% of the display substrate 10 area
is covered with the iLEDs 22. An exemplary 8k.times.4k display of
the same size with same-sized iLEDs 22 will still have less than 1%
of the display substrate 10 area covered by iLEDs 22.
Since, according to certain embodiments of the present invention,
only a relatively small area of the display substrate 10 is covered
with micro-iLEDs 22 and conductors 24, a relatively large portion
of the display substrate 10 can be filled with holes 30. For
example, the holes 30 in the display substrate 10 can cover more
than or equal to 75%, 50%, 25%, 12.5%, 10%, 5%, 2%, or 1% of the
minimum contiguous convex display area 12.
In certain embodiments of the present invention, an iLED display 99
is a matrix-addressed iLED display 99 having row-select and
column-data lines (e.g., conductors 24). Each iLED 22 is controlled
by a row-select line in combination with a column-data line. In
some embodiments, a passive-matrix control method is used to
control the pixels 20 (and iLEDs 22 in each pixel 20) directly
through the conductors 24, as illustrated in FIGS. 1-6. In some
embodiments, iLEDs 22 are disposed directly on a display substrate
10 (e.g., as shown in FIG. 1). In some embodiments, iLEDs 22, for
example iLEDs 22 in a pixel 20, are disposed and electrically
connected directly on a pixel substrate 26 and the pixel substrates
26 are in turn disposed and electrically connected on a display
substrate 10 (e.g., as shown in FIG. 8).
In some embodiments, referring to FIGS. 9, 10A, 10B, and 11, an
iLED display 99 is an active-matrix display having a pixel
controller 25 with a control circuit 27 provided for each pixel 20.
The pixel controller 25 is disposed in, on, or over the display
substrate 10 in association with one or more iLEDs 22 in the pixel
20 and is electrically connected (e.g., with conductors 24, not
shown) to the one or more iLEDs 22 to control the one or more iLEDs
22 using signals provided on the conductors 24.
In some embodiments, iLEDs 22 and a pixel controller 25 are
disposed directly on a display substrate 10 (e.g., as shown in FIG.
9). In some embodiments and as illustrated in FIGS. 10A, 10B, and
11, the components of a pixel 20, for example including a pixel
controller 25 and iLED light emitters 22R, 22G, 22B are disposed on
a pixel substrate 26 (e.g., as shown in FIG. 10A) and the pixel
substrate 26 is disposed on a display substrate 10 (e.g., as shown
in FIG. 11). In FIG. 10A, a pixel controller 25 is provided in a
separate integrated circuit on a pixel substrate 26, for example
micro-transfer printed from a native source wafer to the non-native
pixel substrate 26 and electrically connected with fine,
high-resolution electrical conductors 24. In FIG. 10B, the pixel
substrate 26 is a semiconductor substrate and the pixel controller
25 is provided in a circuit formed in or on the pixel substrate 26,
so that the pixel controller 25 is native to the pixel substrate
26, and electrically connected with fine, high-resolution
electrical conductors 24.
Structures and elements in accordance with certain embodiments of
the present invention can be made and assembled using
micro-transfer printing methods and materials. In some embodiments,
iLEDs 22 are prepared on a native source wafer, for example a
sapphire wafer with compound semiconductors such as GaN thereon,
each type of iLED 22 prepared on a different source wafer and
released for micro-transfer printing with one or more tethers 28
(FIG. 10A shows one tether 28) physically connecting each iLED 22
to an anchor portion of the source wafer. Any pixel controller 25
provided in a separate integrated circuit, for example comprising
silicon CMOS circuits, can similarly be prepared on a source wafer
such as a silicon wafer. In certain embodiments, iLEDs 22 and any
pixel controller 25 components are then contacted with a
micro-transfer printing stamp (e.g., successively) to fracture or
otherwise break the tethers 28 and adhere the components to the
stamp, the stamp is transferred to a non-native destination
substrate such as a display substrate 10, and the components are
contacted and adhered to the destination substrate. A different
micro-transfer printing step can be used with each different source
wafer. When micro-transfer printing components directly from the
source wafers to the destination substrate (e.g., display substrate
10), each micro-transfer printed component will have a substrate
and form a fractured tether 28 such as that shown in FIGS. 10A,
10B.
If, in some embodiments, the components are first micro-transfer
printed to non-native pixel substrates 26 (FIG. 10A), the pixel
substrates 26 themselves can be, but are not necessarily,
micro-transfer printed to a non-native destination substrate 10
using the same released structure with a tether 28 and
micro-transfer printing process resulting in the display structure
of FIG. 8 (without a pixel controller 25 in a passive-matrix
configuration) or FIG. 11 (with a pixel controller 25 in an
active-matrix configuration).
An iLED display 99 can have one of a variety of designs having a
variety of resolutions, iLED 22 sizes, and display substrate 10 and
display area 12 sizes. For example, display substrates 10 or tile
substrates 16 ranging from 1 cm by 1 cm to 1 m by 1 m in size are
contemplated. Inorganic light-emitting diodes 22 can be micro-iLEDs
22 and can have a size of one square micron to 500 square microns
(e.g., at least one of a height, a length, and a width from 2 to 5
.mu.m, 5 to 10 .mu.m, 10 to 20 .mu.m, or 20 to 50 .mu.m). In
general, larger iLEDs 22 are most useful with, but are not limited
to, larger display substrates 10. The resolution of iLEDs 22 over a
display substrate 10 can also vary, for example from 50 iLEDs 22
per inch to hundreds of iLEDs 22 per inch, or even thousands of
iLEDs 22 per inch. For example, a three-color display having one
thousand 10 .mu.m.times.10 .mu.m iLEDs 22 per inch (on a 25-micron
pitch) has an aperture ratio of less than 16 percent (including
only the iLEDs 22). Thus, certain embodiments of the present
invention have application in both low-resolution and very
high-resolution displays. An approximately one-inch 128 by 128
pixel display having 3.5 micron by 10-micron micro-iLED 22 emitters
has been constructed and successfully operated as described in U.S.
Patent Application Ser. No. 62/148,603 filed Apr. 16, 2015,
entitled Micro Assembled Micro iLED displays and Lighting Elements.
This iLED display has an aperture ratio (including only the iLEDs)
of less than 1.0%.
According to certain embodiments of the present invention, a
display substrate 10 can include layers formed on an underlying
structure or substrate, for example a rigid or flexible glass or
plastic substrate. In some embodiments, micro-iLEDs 22 are formed
in a layer on a display substrate 10 so that the micro-iLEDs 22 are
native to the display substrate 10. In some embodiments,
micro-iLEDs 22 are transferred from another substrate (such as a
semiconductor source wafer) to a display substrate 10 so that the
micro-iLEDs 22 are non-native to the display substrate 10.
Referring to FIG. 1, the micro-iLEDs 22 are electrically connected
to one or more electrical conductors 24 that electrically connect
two or more of the pixels 20 and conduct power, a ground reference
voltage, or signals for controlling the pixels 20 and the
micro-iLEDs 22. In some embodiments, electrical conductors 24 are
connected to a display controller that is external to a display
substrate 10 (not shown). In some embodiments (not shown), the
display controller is located on the display substrate 10 outside
the display area 12. In certain embodiments, a display controller
controls an iLED display 99 by, for example, providing power, a
ground reference signal, and control signals. For clarity of
illustration, the conductors 24 are omitted from the perspectives
of FIGS. 8, 9, and 11.
As shown in the illustrative embodiments of FIGS. 1 and 9, pixels
20 can form a regular array on a display substrate 10. Each pixel
20 can include a single micro-iLED 22. As shown in FIG. 1, each
pixel 20 can include at least three micro-iLEDs 22, wherein each of
the at least three micro-iLEDs 22 emitting light of different
colors, for example red, green, and blue. In some embodiments, at
least some pixels 20 have an irregular arrangement on a display
substrate 10 (not shown).
Referring to the perspectives of FIGS. 9-11, in certain embodiments
of the present invention, each pixel 20 in the display area 12 of a
display substrate 10 further includes a pixel controller 25. The
pixel controller 25 is electrically connected to the one or more
micro-iLEDs 22 (for example the red-light emitter 22R, the
green-light emitter 22G, and the blue-light emitter 22B) to control
the light output of the one or more micro-iLEDs 22, for example in
response to control signals from a display controller through
electrical conductors 24.
In some embodiments, a pixel controller 25 or micro-iLEDs 22 are
formed in substrates or on supports separate from a display
substrate 10 and disposed directly on the display substrate 10. For
example, micro-iLEDs 22 and/or pixel controllers 25 are separately
formed in a native semiconductor source wafer. The micro-iLEDs 22
or the pixel controller 25 are then removed from the wafer and
transferred, for example using micro transfer printing, to the
display substrate 10. This arrangement has the advantage of
enabling use of a crystalline silicon substrate for the pixel
controller 25 that provides, smaller higher-performance integrated
circuit components than can be made in the amorphous or polysilicon
semiconductor available on a large substrate such as the display
substrate 10.
As shown in the perspectives of FIGS. 10 and 11, in some
embodiments, micro-iLEDs 22 or pixel controllers 25 are located on
or in a pixel substrate 26 smaller than and separate and distinct
from a display substrate 10. Compound micro-assembly can be used to
assemble micro-iLEDs 22 onto a pixel substrate 26 to form a pixel
20 and the pixel 20 is then micro-transfer printed or otherwise
transferred to a display substrate 10. In some embodiments, other
devices, for example pixel controllers 25, are also printed to
pixel substrates 26 to form pixels 20.
In some embodiments, a display substrate 10 can include material,
for example glass or plastic, different from a material in a
semiconductor substrate (e.g., a pixel controller 25 substrate),
for example a semiconductor material such as silicon or a compound
semiconductor. As shown in FIGS. 10 and 11, pixels 20 or a pixel
controller 25 can be located on a pixel substrate 26 with the pixel
substrate 26 separately located on a display substrate 10. In some
embodiments, a pixel controller 25 or micro-iLEDs 22 can be formed
separately on separate semiconductor substrates (native source
wafers), assembled onto a pixel substrate 26, and then the
assembled unit is disposed on a surface of a display substrate 10.
This arrangement has the advantage that the pixels 20 can be
separately tested before they are located on the surface of the
display substrate 10, thus improving yields and reducing costs.
In some embodiments of the present invention, micro-iLEDs 22 have
light-emissive areas or a size of less than 10, 20, 50, or 100
square microns. In some embodiments, micro-iLEDs 22 have at least
one of a height, a length, and a width from 2 to 50 .mu.m (e.g., 2
to 5 .mu.m, 5 to 10 .mu.m, 10 to 20 .mu.m, or 20 to 50 .mu.m). Such
micro-iLEDs 22 have the advantage of a small light-emissive area
compared to their brightness as well as color purity providing
highly saturated display colors and a substantially Lambertian
emission providing a wide viewing angle for the iLED display 99 of
the present invention. In various embodiments, the display area 12
of a display substrate 10 is greater than or equal to eight times,
ten times, twenty times, fifty times, one hundred times, two
hundred times, five hundred times, one thousand, or ten thousand
times the combined light-emissive areas of the iLEDs 22 or the
areas of the iLEDs 22.
Certain embodiments of the present invention can be operated in a
variety of useful ways. In some embodiments, a display controller
provides power, a ground reference, and control signals to pixels
20 in an iLED display 99 through electrical conductors 24. The
signals can provide a passive-matrix control of the micro-iLEDs 22
in the pixels 20 to provide functionality to the iLED display 99.
In some embodiments, pixels 20 include a pixel controller 25. A
display controller is connected to the pixel controller 25 through
electrical conductors 24 and provides control signals for operating
the micro-iLEDs 22 in the pixels 20, for example in an
active-matrix control configuration. In some embodiments, a pixel
controller 25 includes analog, digital, or mixed-signal circuitry
and can control micro-iLEDs 22 in response to a display controller
to emit light in an image-wise fashion to provide a display, for
example displaying images, graphics, text, or other
information.
In methods according to certain embodiments of the present
invention, a display substrate 10 is provided with holes 30. The
display substrate 10 can be any conventional substrate such as
glass, plastic, or metal or include such materials. The holes 30
can be made by etching, ablation, scribing and breaking, or
molding, among various techniques. The display substrate 10 can be
transparent, for example having a transmissivity greater than or
equal to 50%, 80%, 90%, or 95% for visible light. A display
substrate 10 usefully has two opposing smooth sides suitable for,
for example, material deposition, photolithographic processing, or
micro-transfer printing of micro-iLEDs 22. A display substrate 10
can have a size of a conventional display, for example a rectangle
with a diagonal of a few centimeters to one or more meters and a
thickness of at least 0.1 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, or 20 mm.
Such substrates are commercially available. Before, after, or at
the same time as a display substrate 10 is provided, iLEDs 22
(e.g., micro-iLEDs 22) are provided, for example using
photolithographic integrated circuit processes on semiconductor
substrates. The micro-iLED semiconductor substrates are much
smaller than and separate and distinct from the display substrate
10 or pixel substrates 26. Pixel substrates 26 can comprise
material similar to material comprised in the display substrate
10.
Electrical conductors 24 can be formed on a display substrate 10
using photolithographic and display substrate 10 processing
techniques, for example photolithographic processes employing metal
or metal oxide deposition using evaporation or sputtering, curable
resin coatings (e.g., SU8), positive or negative photo-resist
coating, radiation (e.g., ultraviolet radiation) exposure through a
patterned mask, and etching methods to form patterned metal
structures, vias, insulating layers, and electrical
interconnections. Inkjet and screen-printing deposition processes
and materials can be used to form patterned conductors or other
electrical elements.
Electrical conductors 24, or wires, can be fine interconnections,
for example having a width of less than 50 microns, less than 20
microns, less than 10 microns, less than five microns, less than
two microns, or less than one micron. In some embodiments, wires
can include one or more crude lithography interconnections having a
width from 2 .mu.m to 2 mm, wherein each crude lithography
interconnection is electrically connected to at least one of a
plurality of pixels 20 on a display substrate 10. In some
embodiments, fine interconnections are provided on pixel substrates
26 using relatively high-resolution photolithographic methods and
materials and the coarse interconnections are provided on a display
substrate 10 using relatively low-resolution printed circuit board
methods and materials.
In some embodiments, iLEDs (e.g., micro-iLEDs 22) are transfer
printed to a display substrate 10 in one or more transfers. For a
discussion of micro-transfer printing techniques, see U.S. Pat.
Nos. 8,722,458, 7,622,367 and 8,506,867, the disclosure of each of
which is hereby incorporated by reference. In some embodiments,
micro-iLEDs 22 are electrically connected to conductors 24 and
display substrate contact pads 44 on a display substrate 10 by the
process of micro-transfer printing, using connection posts formed
with the micro-iLEDs 22, as described in U.S. Pat. No. 8,889,485.
In certain embodiments, transferred micro-iLEDs 22 are
interconnected to conductors 24 and display substrate contact pads
44 on a display substrate 10 using photolithographic or printed
circuit board materials and methods, to enable a display controller
to electrically interact with micro-iLEDs 22 to emit light in an
iLED display 99. In some embodiments, transfer or construction of
micro-iLEDs 22 is performed before or after all electrical
conductors 24 are in place. Thus, in some embodiments, the
construction of electrical conductors 24 can be performed before
micro-iLEDs 22 are printed or after micro-iLEDs 22 are printed. In
some embodiments, a display controller is externally located (for
example on a separate printed circuit board substrate) and
electrically connected to electrical conductors 24 using
connectors, ribbon cables, or the like. In some embodiments, a
display controller is affixed to a display substrate 10 outside the
display area 12 and electrically connected to electrical conductors
24 using wires and buses, for example using surface mount and
soldering technology (not shown).
Referring to FIGS. 9, 10A, 10B, and 11, in some embodiments, a
pixel controller 25 is provided, for example using semiconductor
integrated circuit processes. A pixel controller 25 can be provided
at the same time as, before, or after micro-iLEDs 22, on separate
semiconductor wafers, or on the same semiconductor wafer. Referring
to FIG. 9, the micro-iLEDs 22 and the pixel controller 25 are
transfer printed to the display substrate 10, either in a common
transfer step or separate transfer steps from the same or different
semiconductor wafers.
Referring to FIGS. 10A, 10B, and 11, the pixel substrate 26 is
provided in addition to providing the display substrate 10,
providing the micro-iLEDs 22, and providing the pixel controller
25. The pixel substrate 26 can, for example, be similar to the
display substrate 10 (e.g. made of glass or plastic) but in a much
smaller size, for example having an area of 50 square microns, 100
square microns, 500 square microns, or 1 square mm and can be only
a few microns thick, for example 5 microns, 10 microns, 20 microns,
or 50 microns. The iLEDs (e.g., micro-iLEDs 22) and, optionally,
the pixel controller 25 (as shown in FIGS. 10A and 11) are transfer
printed onto the pixel substrate 26 using one or more transfers
from one or more semiconductor wafers to form a pixel 20 with a
pixel substrate 26 separate from the display substrate 10, the
substrate of the pixel controller 25, and the substrates of the
micro-iLEDs 22. In some embodiments, as illustrated in FIG. 10B, a
pixel substrate 26 includes a semiconductor and micro-iLEDs 22 or a
pixel controller 25 and, optionally, some electrical conductors 24,
are formed in the pixel substrate 26 to electrically interconnect
the micro-iLEDs 22 and the control circuit 27, for example using
photolithographic processes and fine interconnections. Optionally,
the pixels 20 on the pixel substrates 26 are tested and accepted,
repaired, or discarded. The pixels 20 are transfer printed or
otherwise assembled onto the display substrate 10 and then
electrically interconnected to contact pads 44 on the display
substrate 10 for connection to the display controller.
Referring to FIG. 13, in some embodiments of the present invention,
holes 30 are located on a tile substrate edge 18 and, in certain
embodiments, can be aligned to form larger holes 30 in and between
the tile substrates 16. In some such embodiments, an iLED display
99 comprises a plurality of display substrates 10 or tile
substrates 16 disposed in a common plane or on a common surface.
Each tile substrate 16 comprises a display area 12 and one or more
tile substrate edges 18. A tile substrate edge 18 of each tile
substrate 16 is disposed adjacent to a tile substrate edge 18 of
another tile substrate 16. A plurality of inorganic light-emitting
diodes (e.g., micro-iLEDs 22) is disposed on, in, or over each tile
substrate 16 in an array (e.g., a regular array) in the display
area 12 and one or more holes 30 extend through one or more tile
substrate 16 at the tile substrate edge 18. For example, a hole 30
that is a notch or indentation on one tile substrate edge 18 of a
tile substrate 16 may be adjacent (e.g., abutted, in contact) with
a tile substrate edge 18 of another tile substrate 16 that does not
have a notch or indentation. In some embodiments, two adjacent tile
substrate 16 having adjacent tile substrate edges 18 each have a
hole 30 (e.g., notch or indentation) extending through the tile
substrate 16 at the tile substrate edge 18 and the holes 30 of the
adjacent tile substrate 16 overlap to form a larger hole 30.
In the context of a tiled iLED display 99, a hole 30 on or in the
tile substrate edge 18 can be a notch or other indentation in the
tile substrate 16 that extends through the tile substrate 16. In
certain embodiments, when two or more tiles 14 are abutted, the
notch or indentation forms a contiguous hole 30 that is completely
surrounded by the tile substrates 16 of the two or more abutted
tiles 14. If both tile substrates 16 have adjoining, adjacent, or
in contact holes 30 (e.g., notches or indentations), the resulting
hole 30 is the combination of the holes 30 (notches or
indentations) of the adjoining holes 30 of each the two or more
tiles 14 and is larger than the hole 30 (notch or other
indentation) in each individual tile substrate edge 18. The holes
30 in the tile substrate edges 18 of the two or more tiles can be
on a corner of the tiles 14.
Methods of forming micro-transfer printable structures are
described, for example, in the paper "AMOLED Displays using
Transfer-Printed Integrated Circuits" (Journal of the Society for
Information Display, 2011, DOI #10.1889/JSID19.4.335,
1071-0922/11/1904-0335, pages 335-341) and U.S. Pat. No. 8,889,485,
referenced above. For a discussion of micro-transfer printing
techniques see, U.S. Pat. Nos. 8,722,458, 7,622,367 and 8,506,867,
the disclosure of each of which is hereby incorporated by reference
in its entirety. Micro-transfer printing using compound
micro-assembly structures and methods can also be used with certain
embodiments of the present invention, for example, as described in
U.S. patent application Ser. No. 14/822,868, filed Aug. 10, 2015,
entitled Compound Micro Assembly Strategies and Devices, the
disclosure of which is hereby incorporated by reference in its
entirety. Additional details useful in understanding and performing
aspects of the present invention are described in U.S. patent
application Ser. No. 14/743,981, filed Jun. 18, 2015, entitled
Micro Assembled iLED displays and Lighting Elements, the disclosure
of which is hereby incorporated by reference in its entirety.
By employing the multi-step transfer, test, or assembly process of
FIGS. 10A, 10B, and 11, increased yields can be achieved and thus
reduced costs for certain embodiments of the present invention.
As is understood by those skilled in the art, the terms "over",
"under", "above", "below", "beneath", and "on" are relative terms
and can be interchanged in reference to different orientations of
the layers, elements, and substrates included in the present
invention. For example, a first layer on a second layer, in some
embodiments means a first layer directly on and in contact with a
second layer. In other embodiments, a first layer on a second layer
can include another layer there between. Furthermore, the
designations of "row" or "column" with respect to matrix addressing
are arbitrary and can be exchanged.
Having described certain embodiments, it will now become apparent
to one of skill in the art that other embodiments incorporating the
concepts of the disclosure may be used. Therefore, the invention
should not be limited to the described embodiments, but rather
should be limited only by the spirit and scope of the following
claims.
Throughout the description, where apparatus and systems are
described as having, including, or comprising specific components,
or where processes and methods are described as having, including,
or comprising specific steps, it is contemplated that,
additionally, there are apparatus, and systems of the disclosed
technology that consist essentially of, or consist of, the recited
components, and that there are processes and methods according to
the disclosed technology that consist essentially of, or consist
of, the recited processing steps.
It should be understood that the order of steps or order for
performing certain action is immaterial so long as the disclosed
technology remains operable. Moreover, two or more steps or actions
in some circumstances can be conducted simultaneously. The
invention has been described in detail with particular reference to
certain embodiments thereof, but it will be understood that
variations and modifications can be effected within the spirit and
scope of the invention.
PARTS LIST
10 display substrate 12 minimum contiguous convex display area 14
tile 16 tile substrate 18 tile substrate edge 20 pixel 22 inorganic
light-emitting diode/micro-iLED 22R red-light emitter 22G
green-light emitter 22B blue-light emitter 24 conductor 25 pixel
controller 26 pixel substrate 27 control circuit 28 tether 30 hole
32 foam 34 flexible sheet 36 audio loudspeaker 40 iLED contact pad
42 electrode 44 display substrate contact pad 46 dielectric 48
reflective layer 60 light 70 row- or column-control circuit 80 via
99 inorganic light-emitting diode (iLED) display
* * * * *